Hi, thanks for change de rate and your words.
7Gb is a lot of information and if you crawl by content it surely takes too much time to process and PHP ends up giving timeout.
You can try increasing the PHP timeout in your Plesk settings. I can’t help you there but you will find a lot of information on Google on how to do it.
I would also do a deep clean of the whole database to help everything improve performance, (after doing backups).
Lastly, you may have to try different configurations in a deletion campaign to see what options work best for you. If there are no duplicates the process will go through the entire DB, then the longer the process takes because it never reaches the limit of 25.
Esteban